Mechanical watch movement

ABSTRACT

A mechanical watch movement having a base-plate and at least one bridge fastened to the base-plate. The base-plate, when viewed in plan, is in the shape of a square having its corners cut off by a circle concentric with the square. Other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square.

I Unlted States Patent 1 1 1111 3,881,312

Bachmann May 6, 1975 [54] MECHANICAL WATCH MOVEMENT FOREIGN PATENTS OR APPLICATIONS 1 lnvemorl Rachmann, Betflach 153,579 11/1932 Switzerland 58/88 R Swnzerland 1,207,289 12/1965 Germany 58/59 [73] Assignee: Ebauches Betllach S.A., Bettlach,

Switzerland Primary ExaminerGeorge H. Miller, Jr. Attorney, Agent, or Firm-Stevens Davis, Miller & [22] F1led. Apr. 30, 1974 Mosher [21] Appl. N0.: 465,663

[57] ABSTRACT 30 F l' t' P 't D t I orelgn Ion y a a A mechanical watch movement having a base-plate May H, [973 Swltzerland 6730/73 and at least one bridge fastened to the basevlata The base-plate, when viewed in plan, is in the shape of a [2?] square having its comers cut Off by a circle Concentric [58] F11. 58 59 8; R with the Square other pans ofthe movement are fip 1 0 l ted within an imaginary cylindrical surface tangent t0 References Cited the sides of the square.

UNITED STATES PATENTS 2/l970 Wuthrich 1. 58/59 UK 8 Claims, 3 Drawing Figures PATENTEDNAY 5:915 3,881,13 1 2 sum 10F 3 PATENTEUHAY s 1975 r 3, 88 1,312

SHEET 3 OF 3 FlG.3

5557 Ck O MECHANICAL WATCH MOVEMENT This invention relates to a mechanical watch movement comprising a base-plate and at least one bridge fastened to the base-plate by pillars.

The object of this invention is to increase the efficiency of watch-movement manufacture. particularly the manufacture of a base-plate, by enabling the massproduction of rough-blanked parts which can then be lathe-tu rned to various diameters in order to yield baseplates of different calibers.

To this end. there is provided according to the present invention a mechanical watch movement of the aforementioned type wherein the base-plate. viewed in plan. is in the shape of a square having its corners cut off by a circle concentric with the square, and the other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square.

Other objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment thereof. taken in conjunction with the accompanying drawings. in which:

FIG. 1 is a top plan view ofa preferred embodiment,

FIG. 2 is a section taken on the line ll-Il of FIG. 1, and

FIG. 3 is a bottom plan view, the parts mounted on the base-plate being removed.

The watch movement shown in the drawing is designed so that it can be manufactured by the fastest and most efficient possible means. To this end, all the elements of this movement have been simplified. they have been reduced in number. and their form has been so chosen as to facilitate both their manufacture and their assembly.

As will be seen in FIG. 1, the movement comprises a base-plate l, a barrel-and wheel-train bridge 2. a bail ance-cock 3. and between these frame elements, the members of the wheel-train. viz., a barrel 4 (FIG. 2), an eccentric center-wheel 5, a third wheel 6, a central fourth wheel 7. an escape wheel 8, a pallet 9, and an oscillating system with balance and balance-spring [0. The dial-train will be described further on.

The winding and setting mechanism comprises a sliding crown-wheel ll which rests on the balance-cock 3, placed a little lower than the bridge 2, a stem 12 machined with a pinion toothing l3, and a setting-wheel (not shown in FIG. 1) which pivots on the lower face of the base-plate l. The stem is held in place by a resilient plate 14 which partly extends under the balancecock 3 and which is fastened around a cylindrical hearing surface of one of the pillars supporting the balancecock 3.

Whereas the balance-cock 3 is fastened on two pillars integral with the base-plate l by means of screws [5, the bridge 2 is fastened to the base-plate l by three pillars 16a. 16h. 160 which are riveted to the base-plate and to the bridge 2. as can be seen in FIG. 2. The cylindrical ends of the pillars are engaged in circular openings cut out of the base-plate l and the bridge 2 and are then turned back laterally over the outer surfaces of those frame elements. thus ensuring the rigid and permanent attachment of those elements to the frame of the movement described.

The basc-plate when viewed in plan, has the shape ofa square intersected by a circle concentric with that square. Thus its outer edge consists of four straight-line elements and four concentric arcs of the same diameter. In one of the straight sides. there is a notch l7 serving to position the part during various machining operations which it undergoes in the course of manufacture. This manufacturing process is as follows: in a strip of metal, e.g., brass. a square piece is first blanked, possibly with its corners slightly rounded, the length ofa side being equal to that which the part is to have in its fm ished state. At the same time as the outline of the plate is blanked, the various holes are punched which are necessary for performing pivoting. fastening. or checking functions. These details will not be described here. It will be noted. however, that holes l9 and 20, situated in the vicinity of the rounded edges of the baseplate, are intended for the positioning and centering of the part. The bauche of the base-plate thus blanked is then finished by lathe-turning according to two slightly different diameters so as to form projecting edges 18 which take up only a portion of the thickness of the base-plate and which will serve to position and support the movement in the watch-case or on its fitting-wing.

The base-plate then undergoes milling operations for producing various recesses (FIG. 3), its inner face remaining flat. Only the elements which are mounted on the outer face of the base-plate are partially or completely sunk into recesses, as will be seen further on. These recesses are all situated within a circle tangent to the four straight edges of the base-plate. and the holes 19 and 20 are situated in a zone lying outside that circle, in portions of thc base-plate where it retains its full thickness. The elements of the movement which are mounted on the inner face of the base-plate. viz.. the entire wheel-train and the frame elements, as well as the mechanism, are all fitted within an imaginary cylindrical surface tangent to the straight edges of the base-plate. so that the zones in the vicinity of the rounded corners are completely free.

One of the particularities of the base-plate l is that the difference between the diameters of the circle which determines the rounding of the edges 18 and of the circle tangent to the four straight sides is greater than the difference in size between two standard calibers of watch movements. Thus if, in the base-plate shown in the drawing. the diameter of the circle which determines the rounded edges 18 is that of the baseplate edge of a 13" caliber, the diameter corresponding to a l2"' caliber will be greater than the circle circumscribed around the other parts of the movement and tangent to the straight sides of the square. so that the same base-plate may also have corners turned along arcs with a diameter corresponding to the 12" caliber. while at the same time having the same recesses and the same holes as the base-plate 1. In this case. holes 19 and 20 will disappear from the basc-plate intended for the 12 caliber without the arrangement of the rest of the movement being changed in any way. Therefore. the lathe on which the edges 18 are machined may be equipped with part-holders which fix the ebauches of base-plates between the centers of their straight sides and which are the same whether it is desired to finish the ebauches in the form of parts for a 13" caliber or for a 12" caliber. This efficiency measure lowers the cost price of the base-plates to a considerable extent.

Base-plate l bears in its outer face two setting-wheels 52 and 53 which mesh with one another and serve to actuate the minute-wheel during setting. These two setting-wheels are cup-shaped blanked and stamped parts. each of which pivots on one of two collets, 54 and 55 in which there are central openings which go all the way through the base-plate at the bottom of a recess intended to receive the respective setting-wheel. Each of these setting-wheels is held in place by a washer 56, 57 which rests on a shoulder turned at the top of the collet and which is fixed by rubbing down the upper collar of the collet.

A recess 58 milled in the outer face of the plate is annular in shape, and its outside diameter extends almost up to the sides of the plate. it is intended to receive a date-ring with which the movement described will be equipped.

The bridge 2 and the balance'coek 3 are generally flat parts having holes but no recesses. A square hole 2] in bridge 2 corresponds to two square holes in the baseplate, and these holes serve to fasten a partial stern cock on which the crown-wheel ll pivots. A similar partial stem cock 22 is held in place between a notch in the balance-cock 3 and a rectangular hole in the baseplate l in the vicinity of the straight side turned toward 3 oclock.

As will be seen in H6. 2, the dial-train presents a particularity which greatly simplifies its manufacture. In this figure can be seen the pillar 16a which connects the base-plate l to the bridge 2, the central fourth wheel 7 with its spindle passing through a pipe 23 fastened to the center of the base-plate l, and the barreldrum 4. The latter has a toothing 24 which is engaged with the pinion of the eccentric center-wheel 5. The drum 4 is further provided with a tubular central hub extending inside the drum in the form of a cylindrical bushing 25, on the one hand, and outside the drum into the vicinity of the base-plate 1 in the form ofa sleeve, on the other hand. The outer portion 26 of the sleeve has an annular groove 27, the bottom of which is broken through along a portion of its periphery so as to form a slot 27a. Engaged within the hub 25, 26 is a barrel-arbor 28 fitted freely to the inside dimensions of the hub. Near its two ends, the arbor 28 passes through two openings 29 and 30 in the bridge 2 and in the base-plate 1, respectively, thus enabling the barrel 4 to pivot. At the level of the groove 27, the arbor 28 also has a groove 31 with a trapezoidal profile, in the bottom of which rests one of the arms of a bolt 32, the outer arm of which is engaged in the groove 27. This bolt 32, of a hairpin shape. forms a friction coupling between the arbor 28 and the barrel 4. At the same time, it fixes the arbor 28 axially. As the openings 29 and 30 have the same diameter as the opening of the hub 25, 26, the arbor 28 can thus slide axially and be removed. The bolt 32 is placed on the barrel 4 before the latter is fitted in the movement, and it resiliently presses the arbor 28 against the inner surface of the hub 25, 26. The inner edge of its arm which is in contact with the bottom of the groove 27 has a concave rounding, while the inner edge of the outer arm is straight and rests against the arbor 28 through the opening in groove 27.

At its upper end, the arbor 28 has a frustoconical head 33 provided with a slot. lt can be grasped by this head and extracted from the movement, thus enabling the barrel 4 to be removed laterally for repair or overhaul.

Engaged on the bushing which extends inside the drum 4 is a tubular core 34. it is provided with a stophook 35 for the inner end of the mainspring, and a ratchct wheel 36 is driven onto the upper end of it. Thus the ratchet-wheel 36 acts as a cover for the barrel 4 and extends immediately beneath the bridge 2. The

length of the core 34 is very slightly less than that of the bushing 25 which, with the sleeve 26, determines the axial shake of the barrel assembly on arbor 28.

At its lower end, the arbor 28 has a square 37 which projects from the outer face c the base'plate 1 in a thinner portion of this frame element. The square 37 serves as a connection element between the arbor 28 and a minute-wheel mounted on the outer face of the base-plate I. This minute-wheel is composed of a pinion 38 and a toothed disc 39. The pinion 38 is made by blanking from a circular disc with a square center hole adjusted to the dimensions of the square 37. It has a peripheral toothing which will be machined, preferably by milling, and as seen in the drawing, it has teeth truncated at approximately half of their height and limited by outer faces contained in an imaginary circular cylindrical surface. The toothed disc 39 has a center opening adjusted to the dimensions of this imaginary cylindrical surface, and it is driven onto the pinion 38. Since it is thinner than the pinion 38, it leaves a sufficient portion of the thickness of the teeth alongside it to ensure the meshing of the pinion 38 with an hour-wheel 41, as will be seen in the drawing.

The hour'wheel 41 is itself mounted on a cannonpinion 40 which pivots on the pipe 23 and meshes with the peripheral toothing of the disc 39.

This arrangement makes it possible to use a baseplate in which the differences in height between the various zones are reduced to the minimum. Thus the minutewheel is fitted in a recess in the outer face of the base-plate. It is completely sunk into this recess through the bottom of which the arbor 28 passes, which enables the barrel to pivot in the base-plate. Since, the friction coupling necessary for setting exists between the arbor 28 and the drum 4, the minute-wheel is driven directly by the barrel-arbor owing to the rigid coupling composed of the square hole of the pinion 38 and the corresponding square at the end of the arbor 28. This indirect drive of the hands requires a minimum number of parts, and the arrangement described makes it easy to dismantle both the barrel and the timeindicating members.

The toothed disc 39 will be engaged with a settingwheel, likewise pivoting on the outer face of the baseplate and cooperating with the member of the setting mechanism.

In the event that the movement described is to be constructed to receive hourand minute-indicating members consisting of discs extending beneath the dial and partially appearing in an aperture, instead of the usual hands moving above the dial, the same constituent elements of the minute-wheel may be used. How ever, the pinion 38, rather than being milled with all its teeth truncated, will have a certain number of full teeth regularly distributed around its periphery. The outside diameter of the toothing of the hour-wheel will be slightly less than in the case described above, so that only the full teeth of the minute-wheel pinion mesh with its toothing. The hour-wheel will normally be kept in a fixed position, e.g., by a jumper-spring, and will move by one-twelfth of a revolution per hour, driven by one of the full teeth of the minute-wheel pinion.

In this case. the center opening of the disc 39 will be blanked with notches corresponding to the full teeth of the pinion 38 so that this disc may be driven onto the pinion. Provision might also be made to let the full teeth of the pinion 38 remain only for a portion of their thickness, the disc 39 then having a circular opening driven onto the portions of truncated teeth. This simplitied minute-wheel drives the moving parts 40 and 41 under conditions corresponding to conventional conditions. In particular. despite the fact that the teeth of the pinion 38 are truncated for about half of their height, an hour-wheel with a conventional toothing. such as wheel 41, meshes with them perfectly.

The arrangement of a click 42 for retaining the ratchet-wheel 36 can be seen in FIG. I. The click 42 is a blanked flat plate having an indentation 43 in the form of an arc of about 220 along one of its edges. On the edge of it opposite the indentation 43, the plate 42 had a beak 44 which is slightly inclined with respect to the radial direction determined by the center of the indentation 43 and the end of the beak 44, Two wings, 45 and 46, extend on either side of this beak 44, the wing 46 being limited by a straight edge which comes to rest against the toothing of the ratchet-wheel 36, while the wing 45 extends beyond the edge of the bridge 2.

As will be seen in FIG. 2, the pillar 16a has a first shoulder 47 which serves to position the bridge 2 with respect to the base-plate 1 and, starting at the edge of this shoulder 47, a cylindrical bearing surface 48 limited axially by a second shoulder 49. It is on the cylin drical bearing surface 48 that the indentation 43 of the click 42 is engaged, so that the latter is held axially in place between the inner face of the bridge 2 and the shoulder 49. The beak 44 is engaged in the toothing of the ratchet-wheel 36, and normally, the action of the mainspring presses the wing 46 against this same toothing, so that the ratchet-wheel 36 is blocked. However, if pressure is applied to the wing 45 which projects beyond the bridge 2, the beak 44 is disengaged from the toothing of the ratchet-wheel 36, which allows the mainspring to be let down.

Upon winding, when the stem 12 is turned so that the crown-wheel I] is driven counterclockwise as viewed in FIG. I, this wheel 11 comes to mesh with the toothing of the ratchet-wheel 36 and turns it clockwise. The click 42 pivots so that the beak 44 leaves the toothing. It is then returned by a spring consisting of an arm 50 blanked in the resilient plate 14 and resting on the end of the indentation 43 situated on the same side as the wing 46.

A hole 51 made in the bridge 2 makes it possible to verify whether the click is in place and whether it s properly resting against the ratchet-wheel.

The arrangement of the click 42 which has just been described considerably simplifies the manufacture of the movement for several reasons. First of all, whereas the conventional clicks are generally held in place by a step-screw, the click described here pivots around a cylindrical bearing surface which is lathe-turned directly in one of the pillars of the movement. Thus the manufacture of a part is avoided, and above all, of a threaded part. Moreover, the production ofa click with an indentation in the shape of an arc of more than 180 requires vastly simpler tooling than that ofa click having a hole. Clicks must be made of steel in order to prevent them from wearing out too quickly, and the diameter of the pivot is obviously very small. The tools required for blanking and punching steel plates with a small-diameter hole are extremely delicate and, consequently, highly subject to breakage, as well as being very expensive. The manufacture of a blanking tool having the necessary shape for producing the click 42 is much less expensive, and this tool is much sturdier than one having a punch for cutting out a hole. The tooling costs for manufacturing the click 42, as well as the rejects, are therefore considerably reduced with the arrangement shown in the drawing. Finally, it will be noted that the movement described does not necessitate the manufacture and fitting of a special spring for the click since this spring is blanked in one piece with the one which holds the winding-stem in place. This plate, made of beryllium bronze, for example, performs two functions, and it, too, is very simple to fit in place.

What is claimed is:

l. A mechanical watch movement comprising a baseplate and at least one bridge fastened to the base-plate by pillars, wherein the base'plate, viewed in plan, is in the shape of a square having its corners cut off by a circle concentric with the square, and the other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square.

2. A watch movement in accordance with claim 1, wherein the inner face of the base-plate is flat. while the outer face exhibits recesses and collets for mounting elements of the movement.

3. A watch movement in accordance with claim 1, wherein the outer face of the base-plate exhibits a circular recess coaxial with a hole provided for the pivoting of one end of a barrel-arbor, a minute-wheel being completely sunk within said recess.

4. A watch movement according to claim 1 further comprising positioning holes in the rounded corners of the base-plate within a zone situated outside said imaginary cylindrical surface.

5. A watch movement in accordance with claim I, wherein the difference between the diameter of the circle which determines the outline of the base-plate and the side of the square is greater than the difference between the diameters of two standard circular calibers. the diameter of said circle corresponding to that of the larger caliber.

6. A watch movement in accordance with claim 5, further comprising positioning holes in the rounded corners of the base-plate within a zone situated outside a circle whose diameter corresponds to the smaller of said two calibers.

7. A mechanicalwatch movement comprising a baseplate and at least one bridge fastened to the base-plate by pillars, wherein the base-plate, viewed in plan, is in the shape of a square having its corners cut off by a circle concentric with the square, and the other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square, and wherein the inner face of the base-plate is flat, while the outer face exhibits recesses and collets for mounting elements of the movement, and wherein the base-plate bears on its outer face at least one setting-wheel pivoting on one of said collets and held axially in place by a washer coaxial with the collet and fastened there by rubbing down.

8. A watch movement in accordance with claim 7,

wherein said setting-wheel is stamped in a cup shape. a: 

1. A mechanical watch movement comprising a base-plate and at least one bridge fastened to the base-plate by pillars, wherein the base-plate, viewed in plan, is in the shape of a square having its corners cut off by a circle concentric with the square, and the other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square.
 2. A watch movement in accordance with claim 1, wherein the inner face of the base-plate is flat, while the outer face exhibits recesses and collets for mounting elements of the movement.
 3. A watch movement in accordance with claim 1, wherein the outer face of the base-plate exhibits a circular recess coaxial with a hole provided for the pivoting of one end of a barrel-arbor, a minute-wheel being completely sunk within said recess.
 4. A watch movEment according to claim 1 further comprising positioning holes in the rounded corners of the base-plate within a zone situated outside said imaginary cylindrical surface.
 5. A watch movement in accordance with claim 1, wherein the difference between the diameter of the circle which determines the outline of the base-plate and the side of the square is greater than the difference between the diameters of two standard circular calibers, the diameter of said circle corresponding to that of the larger caliber.
 6. A watch movement in accordance with claim 5, further comprising positioning holes in the rounded corners of the base-plate within a zone situated outside a circle whose diameter corresponds to the smaller of said two calibers.
 7. A mechanical watch movement comprising a base-plate and at least one bridge fastened to the base-plate by pillars, wherein the base-plate, viewed in plan, is in the shape of a square having its corners cut off by a circle concentric with the square, and the other parts of the movement are fitted within an imaginary cylindrical surface tangent to the sides of the square, and wherein the inner face of the base-plate is flat, while the outer face exhibits recesses and collets for mounting elements of the movement, and wherein the base-plate bears on its outer face at least one setting-wheel pivoting on one of said collets and held axially in place by a washer coaxial with the collet and fastened there by rubbing down.
 8. A watch movement in accordance with claim 7, wherein said setting-wheel is stamped in a cup shape. 